1. Field of the Invention
The present invention relates generally to methods and apparatus for controlling brain wave frequencies and to therapeutic uses of such methods and apparatus.
Human brains disturbed by social, mechanical, chemical or other trauma become both restricted in their electrical and chemical activity and hypersensitive to internal and external events and stimuli. In one of its aspects, the present invention pertains to the assessment and amelioration of functioning after psychological and mechanical trauma, or the enhancement of typical brain functioning, through the disruption of the restriction and rigidity of neural activity.
2. Description of Related Art
In the 1960's and early 1970's, Robert Monroe of the Monroe Institute of Applied Sciences explored the effects of sound on the brain and discovered that he could produce a driving or entrainment of brain waves. Dr. Gerald Oster, a biophysicist, also investigating the effects of sound on the brain, discovered that pulsations called binaural beats occurred in the brain when tones of different frequencies were presented separately to each ear. The beat frequency equals the frequency difference between the two tones. Both Monroe and Oster began using electronic oscillators to provide tones with frequency, purity and intensity that can be precisely controlled.
U.S. Pat. No. 3,884,218 to Robert A. Monroe shows a method for inducing sleep by amplitude modulating a pleasing sound with a delta-rhythm signal which is referred to as an "EEG sleep signal."
U.S. Pat. No. 4,191,175 to Nagle shows a method and apparatus for repetitively "producing a noise-like signal for inducing a hypnotic or anesthetic effect. . ." by creating frequency bursts of digital pulses that are then passed through a pink noise filter to get rid of frequencies above a certain cut-off. The resultant signal is then passed through a band pass filter and used to drive an audible signal source.
An apparatus for electrophysiological stimulation is shown in U.S. Pat. No. 4,227,516 to Meland et al. in which a first signal above the delta-beta frequency range is modulated by signal within that range and applied to electrodes on the forehead of a user.
A learning-relaxation device of U.S. Pat. No. 4,315,502 has both lights for pulsing signals and sound means for a pulsing sound signal as well as a control means which can individually vary the light and sound signals.
U.S. Pat. No. 4,834,701 to Masaki shows a device similar to those used by Monroe and Oster with first and second generators with frequencies above 16 hertz and a frequency difference of 4 to 16 hertz sounded to lower the brain wave frequency of a user. The term "entrainment" began to be accepted for such devices: "This phenomenon, in which one regular cycle locks into another, is now called entrainment, or mode locking." (Gleick, Chaos: Making of a New Science 1987, Penguin Books, p. 293) An article entitled "Alpha Brain Waves & Biofeedback Training" in the December 1972 Popular Electronics show a system that uses a person's own EEG signal to modulate a tone generator which, in turn, then drives a speaker heard by the same person. The device allowed a person to "hear" his or her own brain signals in an attempt to voluntarily control the frequency. A similar device that allows a person to "see" his or her own brain waves is shown in an article entitled "Mind Power: Alpha" in the July 1976 Radio-Electronics.
U.S. Pat. No. 5,036,858 to John L. Carter and Harold L. Russell shows the use of EEG electrodes attached to the head of the user along with an amplifier for determining a current brain wave frequency of a user, which is communicated to a computer processor. A new frequency is generated which is between the current brain wave frequency and a desired brain wave frequency and is within a predetermined range of the current brain wave frequency. This has become known as electroencephalographic entrainment feedback if it is used to "lock" the current brain wave frequency into a desired frequency.
Prior methods for assessment of neural function involve radiographic, magnetic, electrical and nuclear evaluations with eyes open or eyes closed states, or at best, the neuronal or other activity evoked under different conditions such as reading, drawing, doing arithmetic, etc. Static frequency stimulation, even that steady frequency stimulation which alternates from time to time, is used to assess the presence and kind of seizure activity.
Methods of treatment have in many ways attempted to ameliorate brain functioning by either providing the brain with a faithful and accurate picture of its activity, or with a means of targeting a desired frequency, range of frequencies, or relationship among frequencies, or have targeted theoretically and empirically derived frequency states as a goal of training or therapy. Methods using feedback have largely involved conscious, voluntary processes in the amelioration of neural functioning. Such methods have not fitted the stimulation frequencies to real-time measurements of neural frequency. They have taken as a goal to feedback to the brain information as to success at reaching target neural activity. These methods require conscious attention, concentration, analysis and learning.